Python: Minimum absolute sum of two integers in an Array

So I was given this problem and figured I would share my solution for others. I believe the Time Complexity to be O(n log n) due to Quicksort being O(n log n). I could be wrong though!

'''

Created on 10/01/2014

# My first foray in python

# min_abs_sum_of_two takes an Integer Array and returns the lowest absolute sum of two integers

# I did not include checking for the following: array length, non integer characters.

@author: BeauR

'''

import time

import sys

def min_abs_sum_of_two(listOfNums):

    #init y as last array place

    y = len(listOfNums)-1

    #init x as first array place

    x = 0

    #set current min to arbitrary max possible integer

    currentMin = sys.maxsize

    #quicksort array into ascending order

    quicksort(listOfNums, x, y)

    #while x is less than y to ensure they never overlap array places

    while (x < y):

        #if the current calculation is less than currentMin

        if abs(listOfNums[x]+listOfNums[y]) < currentMin:

            #store new minimum

            currentMin = abs(listOfNums[x]+listOfNums[y])

        #if the sum of arr[x] & arr[y] is greater than zero

        #x no longer need to be increased as its at optimum minimum value

        if listOfNums[x]+listOfNums[y] < 0:

            #increment search pointer x

            x = x + 1

        else:

            #decrement search pointer y

            y = y -1

    return(currentMin)

   

def quicksort(list, start, end):

    if start < end:                            # If there are two or more elements...

        split = partition(list, start, end)    # ... partition the sublist...

        quicksort(list, start, split-1)        # ... and sort both halves.

        quicksort(list, split+1, end)

    else:

        return

def partition(myList, start, end):

    pivot = myList[start]

    left = start+1

    right = end

    done = False

    while not done:

        while left <= right and myList[left] <= pivot:

            left = left + 1

        while myList[right] >= pivot and right >=left:
            right = right -1

        if right < left:

            done= True

        else:

            # swap places

            temp=myList[left]

            myList[left]=myList[right]

            myList[right]=temp

    # swap start with myList[right]

    temp=myList[start]

    myList[start]=myList[right]

    myList[right]=temp

    return right

start_time = time.clock()

print(min_abs_sum_of_two(listOfNums = [-6, -5, -4, -3, 1]))

print(time.clock() - start_time, "seconds")